Nebulae Associated with Nebulae Associated with

Ultraluminous X-ray SourcesUltraluminous X-ray Sources

P. Abolmasov,

Special Astrophysical Observatory

Very commonly used ionization diagram

Collisionally excited

(shocks or X-rays):

[NII]6583,6448

[SII]6717,6731

[OI]6300,6364

“High excitation” (ionization potential > 1Ry):

[OIII], HeII

[FeIII], ArIV etc…

Ultraluminous X-ray Sources (ULXs)

LX ≥ 1039 erg/s non-nuclear compact sources

Eddington limit

for ~ 10 M

(usual a for stellar-mass BH)Not AGNe!

Not young SNRs!

(can be ~1040 erg/s bright)

Unknown nature!

Most popular models:

-IMBH with a massive donor star accreting @ 0.01-1 critical (Eddington) rate

-Supercritical accretor like SS433 with a thick disk with a funnel, seen face-on

Observational Properties:

-Luminosities 1039-1041 erg/s in the standard X-ray range (Chandra 0.5-8keV)

-Powerlaw or powerlaw+soft excess (T ~ 0.1-0.2keV) X-ray spectra

-~1 per 20 giant spirals

-Connected to the young stellar population (5-20 Myr…)

-Some have radio counterparts (NGC5408 X-1, HoII X-1)

-Some have point-like optical counterparts identified with OB supergiants

-Some are close to massive star clusters (usually offset by tens of parsecs)

-Many have nebular counterparts (ULX nebulae)

ULX nebulae:

MH9/10, the optical counterpart of HoIX X-1

(Grisé et al., 2006)

-Shock excitation ([SII], [NII], [OI] etc. )

-Large sizes, ~50-500pc

-HeII λ4686 emission (stellar?)

-SNRs? (too powerful)

-Superbubbles? (lack of young stars)

-X-ray ionized nebulae? (requires too much X-rays in some cases!)

What are they?

Ho IX X-1

HoII X-1

NGC6946 ULX1 (=X8, X11)

IC 342 X-1

“Peculiar SNRs”

Our results from the 6m:

Eight ULX nebulae

Two spectrographs :

-- MPFS (panoramic)

-- SCORPIO (long slit)

Medium spectral resolution (Δ ~ 5-10Å)

Spectral range 4000-7200Å

34pc (~1,˝5)

20p

c (~

1˝)

LLX X ≈≈ 2.5 10 2.5 103939 erg/s erg/s (0.5-8.0 keV)(0.5-8.0 keV)

L(HL(H) ) ≈≈ 2 10 2 103838 erg/s erg/s

L(optical lines, total) L(optical lines, total) ≈≈ 2 10 2 103939 erg/s erg/s

Also a bright radio sourceAlso a bright radio source from Blair&Fesen, 1994

MF16 (counterpart of NGC6946 ULX-1):

But: HeIIλ4686 / Hβ ~ 0.2 !!

(HST ACS, filter F658N)

Radio isophotes

(VLA)

X-ray source coordinates:20h 35m 00s.75 +60˚ 11' 30".9

MF16

NGC 6946 galaxy:

D = 5,5 (from 5,1 to 5,9) Mpc

Scd, active star formation

Observations with the 6m SAO telescopeSpectrograph wavelength range,Å spectral seeing,

resolution arcsec

MPFS (panoramic) 4000-7000 ~1000 1,5

SCORPIO (long-slit) 4000-5700 ~2000 1,5

MPFS FOV

Long Slit

1˝

Hα

Hβ [SII](6717+6731)

[OIII](5007+4959)

HeII4686 [NII](6548+6583)

Emission lines’ mapping:

Barycenter shift:

line H : -0,111 -0,088 ±0,013 H : -0,11 -0,10 ±0,02 HeII : 0,72 -0,02 ±0,02 [OIII] : 0,058 0,011 ±0,015 [SII] : -0,116 -0,081 ±0,014 [NII] : -0,061 -0,064 ±0,013

1˝

1˝

Integral spectrum:

MPFS total spectrum

Very rich high-excitation spectrum (HeII, FeIII, OIII) and bright shock-ionized lines (SII, NII, OI).

SCOPRIO spectrum:

Possible interpretations – fast (photoionizing) shock waves or photoionization by a broadband continuum…

[OIII]5007

H

HeII4686H

[OIII]4959[OIII]5007

Two-component lines:

V2-V1 120-130 km/s

Broader component width ~ 200-300km/s

(from Dopita&Sutherland, 1996)

,

,

7.69

866 H precursorS

H shock

FkmV s F

Total luminosity in H (if the shock surface area is given);

Shock velocity estimate from the component ratio:

For a single H line:

VS

precursorShock(cooling matter)

L(Hβ) = (7,2±0,4) 1037 erg/s

Narrow-to-broad components ratio 1,85±0,19kinematics

Additional source of excitation/ionization?

Single Hβ line

nH, cm-3

SHOCK WAVES OR PHOTOIONIZATION?

MF16

MF16

from Evans et al., 1999

Photoionization by power law continuum (labelled by ionization parameter logarithm lgU)

13.6

1

eV

FU d

cn h

Only lgU~-5 can be provided by the extrapolated model for X-ray spectrum (Chandra data, taken from Roberts&Colbert, 2003), lgU~-2.7 needed

B/n1/2 =

Using single recombination line

Total effective recombination coefficient for He++ for Case B

Recombination with HeII4686 emission coefficient

Weakly varying function of physical

conditions

L<228Å ≥ 1039erg/s

L(HeII)=1.6 1037 erg/sHeII4686

Cannot be explained by a shock wave, and an EUV source needed with

L<228Å ≥ 1039erg/s

MF16

Photoionization by power law continuum (labelled by ionization parameter logarithm lgU)

Or X-ray source with L ~ 1041 erg/s or larger!

Pure photoionization models (CLOUDY 96.01 modeling results):

Photoionization best-fit:

lgT(K) = 5.15±0.05

(T~120 000K)

F = 0.6 ± 0.1 erg/cm2/s

fixed X-ray spectrum (best-fit from Roberts&Colbert, 2003), with dilution corresponding to 13pc

+

black body with temperatures (3-30) 104K and integral flux densities 0.3-7.0 erg/cm2/s

=> UV luminosity ~1040erg/s

Central source emitting:

Other high-excitation nebulae:

M101 P098 from the work of Kuntz et al (2001)

High-excitation nebulae: HoII X-1

Bubble nebulae: HoIX X-1

Bubble nebulae: IC342 X-1

HeII4686 accompanied by other high-excitation lines, both allowed and forbidden (MF16)

Both high-excitation and low-excitation lines are enhanced everywhere!

Compare with Baldwin’s picture!

SNRsULXNe

PNe

Seyfert NLRs

Photoionized HII regions

Unification scheme for ULNXe?

Low EUV luminosity / large shell size

(the case of HoIX X-1 and IC342 X-1):

High EUV luminosity / small shell

(the case of MF16):

Shock-ionized shell

X-ray source

Strömgren zone

Very large diffuse shell or no shell at all

(M101 P098)

In the framework of supercritical accretor model:

Supercritical wind photosphere emitting EUV quanta!

Wind photosphere

Thin wind-blown bubble

Lower mass loss:

Higher mass-loss rate:

HST images

B

H+[NII]

W50 (VLA)

Optical filamentsOptical emission of W50:

[OIII]5007 / H ~ 8 ?!!L(H) ~ 1039 erg/s ?!!

50pc

Zealey et al.,1980

Conclusions:

-All the observed ULX nebulae are at least partially shock-powered

-Practically all of them contain signatures of high excitation (bright

HeII, [OIII] lines)

-To explain the spectra of some of them, EUV source is needed even

brighter than the X-ray source

- Many of ULXs most likely have wind/jet activity similar to that of

SS433